repology: return a list of versions instead

to support list options. Returning the first isn't usually desirable.

docs/usage.rst

@@ -570,8 +570,9 @@ repo
 
 subrepo
   Check the version in this subrepo. This field is optional.
-  When ommited all subrepos are queried and first entry
-  (not the highest version) is returned.
+  When ommited all subrepos are queried.
+
+This source supports :ref:`list options`.
 
 Check Anitya
 ~~~~~~~~~~~~

nvchecker_source/repology.py

@@ -26,4 +26,4 @@ async def get_version(name, conf, *, cache, **kwargs):
                               repo=repo, subrepo=subrepo)
 
   versions = [pkg['version'] for pkg in pkgs]
-  return versions[0]
+  return versions